Antenna insulator



Sept. 29, 1942. w PETERS 2,297,430

ANTENNA INSULATOR Filed Sept. 30, 1939 INVENTOR. W/L HELM PETERSATTORNEY.

Patented Sept. 29, 1942 ANTENNA INSULATOB Wilhelm Peters, Berlin,Germany; vested in the Alien Property Custodian Application September80, 1939, Serial No. 297,295 In Germany September 8|, 1988 6 Claims.

This invention relates to a new and novel insulator for supportingcables for antennas.

The high masts for transmitter antennas are anchored by means of steelcables. In order to prevent them from absorbing energy from the antennathey have to be divided into sections which are not in harmonic relationto the transmitted frequency by means of steel cable insulators In thecase of high transmitter powers, the antenna will be surrounded bystrong electrical fields so that these insulators are exposed toconsiderable voltage loads. In addition to the resistance to mechanicaltensions which become very high, especially for instance, in case ofrain,- these insulators should also fulfill the following conditions:The insulator should be subjected primarily to compression stressessince the compression strength ofthe ceramic'insulating material is muchhigher than the tension strength. In the event that an insulator breaks,the antenna mast is to be made safe against toppling over. The cablemust not break. The insulator should have as low a capacity as will bepossible thereby separating favorably the individual cable parts fromone another. The first two conditions were sought to be complied with bymeans of socalled egg insulators known in the prior art.

However, considerable difficulties are encountered in attempting todevelop this form of insulator for high voltages. The disadvantage ofthese insulators resides in that the field lines traverse in certainnumbers the air, as well as the inulating material, so that anovercharging of the air gap and therewith a corona discharge can easilyset in. In order to avoid such a possibility, very large dimensions mustbe used. Therefore, the insulators become heavy and thick so that theycause an unnecessary stress in the cable parts. For this reason,so-called cable hooks have been developed, which can withstand aparticularly high tension stress so that they avoid corona discharges inthe form above mentioned, but these hooks have the disadvantage that inorder to obtain a unilateral compression stress, an insulator pair is tobe employed whereby the bearing links are subjected to unfavorablebending stresses. Therefore, these traverses must have rather largedimensions. Owing to these traverses, and the double arrangement of theinsulatcrs, the structure is extremely heavy. Also, the mounting of thissuspension arrangement causes great difllculties.

In accordance with the present invention, there is employed an insulatorwhich will be subjected that, on the one hand, the field lines passrespectively only in the air or only in the insulator, and on the otherhand, the link which is designed as a hook and transmits the pressure tothe insulator undergoes substantially tension stresses. This inventionwill be more clearly understood by referring to the accompanyingdrawing, in which Fig. 1 shows an example of construction for this novelinsulator. Fig. 2 shows an insulator constructed similar to Fig. 1,except that it is adapted to receive a cable; and Fig. 3 shows asuspension method of two U-shaped half hooks.

Referring now in detail to the drawing, it will be noted that in Fig. 1,the edges on which a high field intensity could appear are completelyavoided. For the sake of propriety, the tension resistance of the breakdown air gap between the armatures of the hook and designated by (1-0will be chosen just as high or somewhat lower than the tensionresistance of the creep distance I 11-27 along the insulator and thepoint of metal to compression stresses and which is so shaped andinsulation contact will be at a different level for adjacent members tothus further reduce the solid dielectric within the electric field. Inthis case, the discharge at overvoltages takes place along the distanceaF-a, so that the insulator proper will not be affected by the arc.According to Fig. 1, the link-like armature parts I and 2 and themetallized bearing surfaces 4 of the insulator 3 are uniformly ground orturned which assures a favorable transmission of the pressure. However,it is also possible to place the cable part around the insulator just asin the case of an ordinary cable. such as shown by way of example, inFig. 2. The cable 2' rests hereby in a semitoroid-like depression orturned groove 4' which is metallized to prevent corona discharges. Fig.3 shows the application'of the invention to a suspension consisting oftwo half links 5, 5' which can be screwed together for example, by aright and left hand thread. These chain links are joined by the two nutst, 6' while the ties are joined with the cables at I.

What is claimed is:

1. An electrical cable insulator comprising a solid approximatelysemi-cylindrical insulator having two flattened paths the lengths ofwhich are less than a semi-circle, said paths being located atintersecting planes and extending in-opposite directions on the outersurface thereof, a pair of metallic members contacting the surfaces ofsaid paths so that the electrical field lines pass either through theair only or through the insulator.

2. An electrical cable insulator comprising a solid approximatelysemi-cylindrical insulator having two flattened paths the lengths ofwhich are less than a semi-circle, said paths being located atintersecting planes and extending in opposite directions on the outersurface thereof, a metallized coating covering the surfaces of both ofsaid paths.

3. An electrical cable insulator comprising a solid approximatelysemi-cylindrical insulator having two flattened paths the peripheryoisaid paths being less than one=halif their diameter, said paths beinglocated at intersecting planes and extending in opposite directions onthe outer surfaces thereof, a central portion of said paths beingconcaved to receive a rod-like member, and a pair of metallic linkmembers contacting the concaved surfaces of said paths.

4. An electrical cable insulator comprising a solid approximatelysemi-cylindrical insulator having two flattened paths the periphery ofsaid paths being less than one-half their diameter, said paths beinglocated at intersecting planes and extending in opposite directions onthe outer surface thereof, a metallized coating covering the surface oisaid flattened paths, and a pair of rodaeamso 5. An electrical cableinsulator comprising a solid approximately semi-cylindrical insulatorhaving two flattened paths the periphery of said paths being less thanone-half their diameter, said paths being located at intersecting planesand extending in opposite directions on the outer surface thereof, acentral portion of said paths being concaved to receive a rod-likemember, a metallized coating covering said concaved surfaces, a pair ofmetallic iinlr members contacting the surfaces of said concaved paths.

6. An electrical cable insulator comprising a pair of solidapproximately semi-cylindrical insulators each having two flattenedpaths the periphery of said paths being less than one-half theirdiameter, said paths being located at intersecting planes and extendingin opposite directions on the outer surface thereof, a pair of metallichalf-link members contacting the surfaces of said paths of eachinsulator, and a pair of coupling members for joining each of saidhalilinl: members together.

WILHEIM PETERS.

